Paper feed system for high-speed printer

ABSTRACT

A paper feed system for a high-speed printer in which a stepping motor drives the platen through a gear train which provides for a one-half line space movement of the platen for every four steps of the stepping motor, the stepping motor having a natural detent when its rotor is manually moved four steps.

United States Patent 1191 1111 3,902,584 Lee et a]. 11 Sept. 2, 1975[54] PAPER FEED SYSTEM FOR HIGH-SPEED 3,272,303 9/ 1966 Pohl 197/114PRINTER 3,583,540 6/1971 Bernard 197 133 x 3,618,738 1l/l971 Boyatt eta]. 197/127 X Inventors: Sen Lin ak n na s 3,643,776 2/1972 Tanaka 197114 Castro Valley, both of Calif. 3,656,041 4/1972 Bonzano 197/133 X3,754,63 8 973 W 7 [73] Assignee: Xerox Corporation, Stamford, 1 ll anget a1 19 I] R Conn OTHER PUBLIICATIONS [22] Filed: Nov. 7, 1973 StepperMotors Philips Product News, A. W. Haydon Co. [2]] Appl. No.: 413,592

Related US. Application Data Continuation of Ser. No. 229,446, Feb. 25,1972, abandoned.

US. Cl. 197/114 R; 197/133 R Int. Cl B41j 19/76 Field of Search 197/1,114 R, 127, 133 R,

197/114 A; 310/49; 27l/DIG. 3,109,114

[56] References Cited UNITED STATES PATENTS 2,844,743 7/1958 Watson310/49 X 3,174,064 3/1965 Muller 310/49 X Primary ExaminerEdgar S. BurrAssistant ExaminerR. T. Rader Attorney, Agent, or FirmJames J. Ralabate;Terry J. Anderson; Leonard Zalman [57] ABSTRACT A paper feed system fora high-speed printer in which a stepping motor drives the platen througha gear train which provides for a onehalf' line space movement of theplaten for every four steps of the stepping motor, the stepping motorhaving a natural detent when its rotor is manually moved four steps.

4 Claims, 3 Drawing Figures PAPER FEED SYSTEM FOR HIGH-SPEED PRINTERThis is a continuation of application Ser. No. 229,446, now abandoned.filed Feb. 25, 1972.

BACKGROUND OF THE INVENTION The present invention relates generally to apaper feed system for a high-speed printer and more specifically to asystem which is compatible with standard manual typing.

Normal office typewriters have their platens detented for one-half thenormal line space. When a printer is to be used as an input/outputdevice where it is to be both manually operated by a keyboard" and alsoto serve as an output device for a computer such line spacing must allowthe computer to utilize its inherently greater capability; for example,for plotting or other unusual print formats.

OBJECT AND SUMMARY OF THE INVENTION It is, therefore, an object of thisinvention to provide a paper feed system for a highspeed printer whichwhile being compatible with standard manual typing is also adaptible tocomplex computer driven printouts.

In accordance with the above object there is provided a paper feedsystem for a high-speed printer in which the line spacing is apredetermined distance consisting of a predetermined number ofincrements. Rotatable platen means receive and feed the paper to beprinted upon and include manual rotating means. Stepping motor means iscoupled to the platen means for incrementing the platen means. Thestepping motor has a plurality of rotor poles and a plurality of statorpoles which may be energized to alternately change polarity to therebyproduce rotation or stepping of the motor. The motor has a naturaldetent for a predetermined number of steps when the rotor is manuallyrotated while the stator poles are continuously energized with aconstant polarity. Gear means are provided to couple the stepping motormeans to the platen means. The gear means have a gear ratio to providefor movement of the platen for a distance equal to one-half the numberof increments which constitute a line space when the stepping motor isdriven by the alternate energiza tion of the poles the predeterminednumber of steps which constitute the natural detent. Thus, when themanual rotating means are actuated and the poles are continuouslyenergized, the natural detent occurs every one-half line space.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. I is a plan view ofa printerembodying the present invention;

FIG. 2 is a cross sectional view taken along line 2-2 of FIG. I; and

FIG. 3 is a simplified schematic of a stepping motor.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT Referring now to FIG.1, an overall view of the printer is illustrated. Mounted on frame is aplaten 11 with left and right knobs 12 and 13 extending therefrom forrolling the platen. More specifically, knobs 12 and 13 are coupled to ashaft 14 which extends through the platen. The shaft is mounted forrotation on frame I0.

A carriage 15 is mounted for linear movement on rods 16 and 17 andincludes a rotary printing wheel having type elements and a hammerassembly for striking a selected type element for printing on papercarried on platen ll. Carriage 15 also includes a ribbon cartridge 18having an inked ribbon which is interposed between a type element andthe paper to be printed upon.

Movement of carriage 15 along the line of printing is accomplished by amotor 21 which is coupled to the carriage by cable system 22. Motor 21has mounted on one end of its shaft a transducer 23 which consists oftwo disks for providing position signals which are used in a servosystem to provide incremental movement of carriage 15. Details of suchtransducer and its associated servo system are claimed in a copendingapplication Ser. No. 157,283 filed June 28, 1971, entitled Apparatus Forthe Measurement of Relative Velocity Between Two Relatively MovableMembers, in the name of Andrew Gabor and assigned to the presentassignee. Overall details of the printer itself including the carriage15 are disclosed and claimed in a copending application Ser. No. 229,314filed Feb. 25, 1972, entitled High-Speed Printer With Intermittent PrintWheel and Carriage Movement in the name of Andrew Gabor and assigned tothe present assignee.

To provide for paper feed, a stepping motor 24 is coupled to the shaft14 by a gear train 26. Stepping motor 24 has mounted on its slhaft asmall pinion gear 27 which drives a larger gear 28 mounted on a shaft 29for rotation on frame 10 which in turn drives a gear 31 mounted on shaft14 which is also the shaft for platen ll. Stepping motor 24 is of thetype as illustrated in FIG. 3 having two fixed poles 32 and 33 heredesignated S and N respectively and a rotor 34 having a number ofrotatable poles; in this specific case, six. In a stepping motor of thetype used in the present invention it is apparent that one step isone-half the distance of rotation between adjacent poles of oppositepolarity. This is because the fixed poles 32 and 33 alternately changepolarity in order to provide the stepping movement, that is, thepolarities reverse alternately with winding 33 changing polarity first,followed by a reversal of'the polarity of winding 32, with the sequencecontinuing with winding 33 changing polarity and then winding 32changing polarity. Thus, assuming a clockwise rotation of rotor 34 ifthe fixed pole 33 changes polarity, the resultant field will have asouth pole between poles 32 and 33 and this resultant field will attractthe north pole of the rotor segment between poles 32 and 33, therebycausing a clockwise rotation of rotor 34. With further changes in thepolarity of windings 32 and 33, the resultant field of the statorwinding will change direction resulting in further clockwise rotation ofrotor 34.

It is also apparent from examination of FIG. 3 that a stepping motor ofthe type used in the present invention has a natural detent of foursteps. Assuming the continuous cnergization of the poles 32 and 33 asillustrated and the manual rotation of rotor 34, the rotor must berotated clockwise four steps before a rotor pole of the correct polaritywill line up with the resultant field of the stator. Thus, a naturaldetent occurs each four steps of the rotor.

Thus. in accordance with the invention the gear train 26 provides formovement of the platen 11 one-half of the nominal line spacing for foursteps of the stepping motor 24. In other words, the platen II is movedfour increments for each one-half line space. This provides a naturaldetent of one-half line space when the knobs l2 and 13 are rotated bythe operator of the printer.

In the preferred embodiment the stepping motor is of the type which maybe purchased from the A. W. Haydon Company of Waterbury, Conneticutunder Model No. IDOS. A motor of this type has 48 steps to therevolution. Also in the preferred embodiment, since the present printerwould be used in the same manner as a standard typewriter and thestandard typewriter halfline space is one-twelfth inch, there will be 48increments per inch of circumferential platen movement. The gear trainshown in FIG. 2 thus provides for 1 inch of movement of the periphery ofthe platen 11 for one revolution of shaft 27. The representationalstepping motor of FIG. 3, which has I2 steps per revolution, couldtheoretically be used but it is found that 48 steps provides for moreadvantageous gear ratios.

Thus, the present invention provides a paper feed system for ahigh-speed printer which is compatible with standard manual typing forproviding a one-half line detent but is adaptable to a computer drivenoutput device since the stepping motor may be driven in one-eighth lineincrements thus providing a great number of increments per inch forplotting and similar purposes.

We claim:

1. A paper feed system for a high-speed printer in which the linespacing is a predetermined distance consisting of a predetermined numberof increments comprising: rotatable platen means for receiving andfeeding paper to be printed upon, said platen means having manualrotating means; stepping motor means coupled to said platen means forincrementing said platen means said stepping motor having a plurality ofrotor poles and a plurality of stator poles which may be energized toalternately change polarity to thereby produce rotation or stepping ofsaid motor having a natural detent for a predetermined number of stepswhen said rotor is manually rotated while said stator poles arecontinuously energized with a constant polarity; and gear means couplingsaid stepping motor means to said platen means, said gear means having agear ratio to provide for movement of said platen for a distance equalto one-half said number of increments which constitute a line space whensaid stepping motor is driven by said alternate energization of saidpoles said predetermined number of steps which constitute said naturaldetent whereby when said manual rotating means are actuated and saidpoles are continuously energized said natural detent occurs everyone-half line space.

2. A system as in claim 1 where said line spacing is one-sixth inch,said one-half line spacing is one-twelfth inch and said number of stepsper revolution is 48.

3. A system as in claim 1 where eight increments constitute a linespace, four increments one-half line space and said natural detentoccurs every four steps,

4. A paper feed system for a printing device in which the line spacingis a predetermined distance comprising:

a rotatable platen for receiving and feeding paper to be printed upon,said platen being adapted for both manual rotation and motor-controlledrotation with a predetermined number of motor-controlled rotationalincrements providing movement of said paper through said predetermineddistance,

a stepping motor coupled to said platen through gear means for achievingsaid motor-controlled incremental rotation of said platen, said motorhaving a plurality of rotor poles and a plurality of stator poles, saidstator poles being coupled to means for alternately changing theirpolarity when said platen is motor-controlled to thereby produce changesin the orientation in the stator field and incremental rotation of saidplaten, said stator poles being continuously energized with a constantpolarity when rotation of said platen is achieved by manual rotation ofsaid rotor poles, said motor having a natural electromagnetic detent fora predetermined fraction of said predetermined number of rotationalincrements,

said gear means having a gear ratio such that said natural detent occurswhen said platen has been manually rotated a distance equal to saidfraction of said predetermined number of rotational increments of saidplaten needed to move said paper through said predetermined distancewhen said platen is motor-controlled.

1. A paper feed system for a high-speed printer in which the linespacing is a predetermined distance consisting of a predetermined numberof increments comprising: rotatable platen means for receiving andfeeding paper to be printed upon, said platen means having manualrotating means; stepping motor means coupled to said platen means forincrementing said platen means said stepping motor having a plurality ofrotor poles and a plurality of stator poles which may be energized toalternately change polarity to thereby produce rotation or stepping ofsaid motor having a natural detent for a predetermined number of stepswhen said rotor is manually rotated while said stator poles arecontinuously energized with a constant polarity; and gear means couplingsaid stepping motor means to said platen means, said gear means having agear ratio to provide for movement of said platen for a distance equalto one-half said number of increments which constitute a line space whensaid stepping motor is driven by said alternate energization of saidpoles said predetermined number of steps which constitute said naturaldetent whereby when said manual rotating means are actuated and saidpoles are continuously energized said natural detent occurs everyone-half line space.
 2. A system as in claim 1 where said line spacingis one-sixth inch, said one-half line spacing is one-twelfth inch andsaid number of steps per revolution is
 48. 3. A system as in claim 1where eight increments constitute a line space, four increments one-halfline space and said natural detent occurs every four steps.
 4. A paperfeed system for a printing device in which the line spacing is apredetermined distance comprising: a rotatable platen for receiving andfeeding paper to be printed upon, said platen being adapted for bothmanual rotation and motor-controlled rotation with a predeterminednumber of motor-controlled rotational increments providing movement ofsaid paper through said predetermined distance, a stepping motor coupledto said platen through gear means for achieving said motor-controlledincremental rotation of said platen, said motor having a plurality ofrotor poles and a plurality of stator poles, said stator poles beingcoupled to means for alternately changing their polarity when saidplaten is motor-controlled to thereby produce changes in the orientationin the stator field and incremental rotation of said platen, said statorpoles being continuously energized with a constant polarity whenrotation of said platen is achieved by manual rotation of said rotorpoles, said motor having a natural electromagnetic detent for apredetermined fraction of said predetermined number of rotationalincrements, said gear means having a gear ratio such that said naturaldetent occurs when said platen has been manually rOtated a distanceequal to said fraction of said predetermined number of rotationalincrements of said platen needed to move said paper through saidpredetermined distance when said platen is motor-controlled.